What are the "rules" of natural winemaking?

Hello there! I'm Dr. Vinifera, but you can call me Vinny. Ask me your toughest wine questions, from the fine points of etiquette to the science of winemaking. And don't worry, I'm no wine snob—you can also ask me those "dumb questions" you're too embarrased to ask your wine geek friends! I hope you find my answers educational, empowering and even amusing. And don't forget to check out my most asked questions and my full archives for all my Q&A classics.
Dear Dr. Vinny,
Does inoculating to start a malolactic fermentation violate the principles of "natural" winemaking?
—Sharen, Woodstock, Vt.
Dear Sharen,
I’m glad you put “natural” in quotes, because it's not a term recognized by the Alcohol and Tobacco Tax and Trade Bureau, which governs wine-labeling laws here in the United States. (Although there has been some effort to define the term in France.) The natural wine trend is a relatively recent winemaking movement that promotes organic or biodynamic viticulture and non-interventionist, additive-free winemaking techniques. These non-interventionist techniques might include native yeast fermentations, the addition of little to no sulfites, and bottling the wine without filtering or fining it. The reason that most wine is made using controlled fermentations, sulfites, fining, filtering, etc., is that those processes help eliminate the possibility of something going wrong and also stabilize the wine to ensure against unwanted blooms of bacteria. Those are some of the many reasons that you don't see large-production natural wines. (Also, most practitioners of natural wine insist that the grapes be harvested by hand.)
As for whether or not inoculating wine with bacteria to kick-start a malolactic fermentation (ML) is a natural-wine no-no, most vintner associations dedicated to natural wine forbid inoculations of any kind, including for ML. (Conversely, they also typically forbid any efforts to prevent ML from occurring.)
Of course, since there's no legal definition of natural wine here in the U.S., no one can stop you from calling it that!
—Dr. Vinny